Liquid to refrigerant heat exchangers are known to be used to transfer thermal energy between a flow of refrigerant and a flow of liquid coolant. Such a heat exchanger can be used as a chiller heat exchanger, wherein heat from a flow of liquid coolant is transferred into a refrigerant to thereby vaporize the refrigerant, resulting in a chilled flow of liquid coolant exiting the heat exchanger. Alternatively, such heat exchangers can be used as a condenser, wherein heat from a flow of superheated refrigerant is transferred into a liquid coolant loop to thereby cool and condense the refrigerant.
Vehicular air conditioning and refrigeration systems have traditionally used air-cooled condensers to accomplish the cooling and condensing of the superheated refrigerant exiting the compressor of the refrigerant system. Such an air-cooled condenser is typically arranged at the front of the vehicle in order to receive the requisite flow of air, which can be provided by the propulsion of the vehicle itself, or by an air moving device, or both. Certain advantages may be obtained, however, by instead using a liquid cooled condenser to accomplish this task. By way of example, engine compartment packaging can be simplified by removing the condenser form the front end of the vehicle.
Challenges are also associated with the implementation of a liquid cooled refrigerant condenser in such an application, though. The temperature of the liquid coolant loop on a vehicle is necessarily higher than the ambient air temperature, so that head pressure of the refrigerant compressor will need to be increased in order to achieve the same amount of subcooling of the refrigerant as was previously achieved using an air-cooled condenser. Proper subcooling is important in reducing the overall energy consumption of such a system, as it increases the available specific enthalpy of the refrigerant flow in the evaporator of the system.
A further challenge is found in the implementation of an integrated receiver within the condenser of the system. A receiver is typically situated along the refrigerant flow path between a condenser section and a subcooler section of the condenser, and functions to ensure that only liquid refrigerant is provided to the expansion device that is typically arranged directly upstream of an evaporator of the system. Excess refrigerant is stored within the receiver in both a liquid and a vapor state, thereby preventing flooding of the condenser with excess liquid refrigerant, which could reduce operating efficiency. As shown and described in U.S. Pat. No. 5,934,102 to DeKuester et al., such a receiver is readily integrated into an air-cooled condenser as an additional cylindrical structure arranged adjacent to one of the cylindrical refrigerant headers.
Such an integration of the receiver is more difficult with a liquid cooled condenser constructed as a plate-style heat exchanger. Published U.S. patent application no. US2014/0224455 and published international patent application no. WO2014/085588 (both to the present applicant) show embodiments of a liquid to refrigerant heat exchanger with such an integrated receiver. In those applications, a separate refrigerant line extends from the condenser section of the heat exchanger to the receiver. This separate refrigerant line can add manufacturing cost and complexity. Thus, there is still room for improvement.